diff --git a/pontarius-xmpp.cabal b/pontarius-xmpp.cabal
--- a/pontarius-xmpp.cabal
+++ b/pontarius-xmpp.cabal
@@ -1,5 +1,5 @@
 Name:          pontarius-xmpp
-Version:       0.5.5
+Version:       0.5.6
 Cabal-Version: >= 1.9.2
 Build-Type:    Custom
 License:       BSD3
diff --git a/source/Network/Xmpp/Concurrent/IQ.hs b/source/Network/Xmpp/Concurrent/IQ.hs
--- a/source/Network/Xmpp/Concurrent/IQ.hs
+++ b/source/Network/Xmpp/Concurrent/IQ.hs
@@ -12,6 +12,7 @@
 import           Control.Monad.Except
 import           Control.Monad.Trans
 import qualified Data.Map as Map
+import qualified Data.Map.Strict as Map.Strict
 import           Data.Maybe
 import           Data.Text (Text)
 import           Data.XML.Pickle
@@ -112,7 +113,7 @@
     atomically $ do
         (byNS, byID) <- readTVar handlers
         iqCh <- newTChan
-        let (present, byNS') = Map.insertLookupWithKey'
+        let (present, byNS') = Map.Strict.insertLookupWithKey
                 (\_ _ old -> old)
                 (tp, ns)
                 iqCh